I think that the influence of 100 engineers is easy to answer: if you set technical direction as an EM or VP of engineering or whatever level E8 is, this means that _indirectly_ many teams will scramble to work to fullfill the exact technical direction you set, which means in turn that managers and senior engineers in those teams will be working on something that you at least had a saying in. That’s how you affect 100s of engineers.
More directly if at some point a bug appears and it’s a blocking issue for releases over an entire department or vertical in the company, if you fix it, you can even affect SEVERAL hundreds of engineers. Apart from these very high level overviews I doubt that E8 folks will look at a chunk of work and start thinking about the number of engineers they’ll affect…
It’s also much more important at that level to be truly product oriented and seeing where the real impact can lie.
Additionally to this, don’t forget the classic “promotion driven development” where features are reinvented or “trivial” changes that affect an entire user base are rolled out, etc